Although the favorites are the same, I actually would disagree that the results are *quantitatively* similar to Castrol's. The comparison is quite interesting, because, as I understand the two sims, they're based on completely different data:

Castrol simulates a team as the sum of its players, using individual stats, whereas

ELO rankings are based entirely on the historical success of the team.

The general difference in the results is that Castrol's odds are much flatter. I.e. favorites are more heavily favored by ELO and underdogs are given a better shot by Castrol. For example, in Group B, Portugal and Denmark are given a 50% and 26% chance of advancing by Castrol, compared to only 29% and 15% by your simulations based on ELO rankings. For Portugal, this is consistent with the much-discussed discrepancy between the club play of Ronaldo and recent results for the international side.